Japan quake threatens setback for nuclear energy

Explosion and meltdown fears at Japan's quake-hit Fukushima nuclear plant renewed debate about the safety of atomic energy Sunday and cast doubt over its future as a clean energy source.

Officials warned that there was a "high possibility" of meltdown at the ageing facility north of Tokyo, which was rocked by an explosion Saturday following an 8.9-strength tremor that sent 10-metre waves bulldozing inland.

Backup cooling systems failed, leaving the core to glow unchecked and sparking fears that fuel could breach the containment shell, leaking dangerous radiation into the densely-populated region that houses 30 million people.

About 200,000 residents were evacuated from a 20-kilometre radius around the plant, which was built in the 1970s and is one of 54 nuclear plants providing about 30 percent of Japan's power.

Operator Tokyo Electric Power Co (TEPCO) insisted radiation was still within safe levels, but mounting internal pressure meant that some vapour had to be released, and it warned another blast might take place in a second reactor.

Anti-nuclear campaigners said the crisis was a timely reminder of the dangers of atomic energy, particularly in a seismic hotspot like Japan, with Greenpeace describing it as an "inherently hazardous" industry.

Tens of thousands of demonstrators took to the streets in Germany over plans to prolong the country's dependency on nuclear power, while Russia ordered a review of its emergency response procedures.

Beijing said it was watching developments closely, having stepped up investment in nuclear power in a bid to slash carbon emissions, with 27 plants being built, 50 in the planning phase and another 110 proposed.

According to the World Nuclear Association there are 443 nuclear reactors operating worldwide, with another 62 under construction, 158 on order and 324 proposed.

Peter Bradford, a former member of the U.S. Nuclear Regulatory Commission, said the disaster was "obviously a significant setback for the so-called nuclear renaissance".

Only the United States and France run more facilities than Japan, but nations including China, India, South Korea, Vietnam, the Philippines and Malaysia all have atomic plans.

"The image of a nuclear power plant blowing up before your eyes on the television screen is a first," said Bradford.

Opposition to nuclear power runs deep in Japan, the only nation to survive an atomic bomb attack. Its nuclear industry has a chequered history, marred by inspection cover-up scandals and fatal accidents.

Two workers were killed after accidentally setting off a self-sustaining reaction at the Tokaimura uranium processing plant in 1999, exposing more than 600 people to radiation in the world's worst atomic disaster since Chernobyl.

Another four were scalded to death at the central Mihama power plant in 2004, while TEPCO, the world's fourth-largest electric utility, was rocked by claims it had falsified dozens of safety inspection reports.

Japanese media were quick to round on Tokyo's response to the Fukushima incident, criticising the government for moving too slowly to direct residents and allay fears of a major nuclear disaster.

But nuclear scientists said facilities had proved incredibly resilient to Friday's tremor, Japan's worst-ever earthquake and one of the 10 largest ever recorded worldwide, adding that the country had few other energy options.

"In the end, you have to ask yourself: do you want to have a zero risk of an accident (at) a nuclear power plant," Temple University Japan's Robert Dujarric told AFP.

"If you do that, you have no nuclear power plant and you have to import more oil from the Middle East, and that's also very dangerous in many ways.

"You can never build a system that can sustain the worst scenario that is five or ten standard deviations from the norm," he added.

Problems at the Fukushima plant, he said, "(don't) necessarily mean it was wrong to build it. It just means that this was an amazing(ly) strong tremor."